msm: mdss: debugfs: xlog: fix xlog early crash

xlog entries may be called before debugfs nodes are created, so
spinlock intitialization should be done during compile time.
Use ktime APIs to avoid other crashes during early boot time.

Change-Id: I5dc8e066b56d26934fd4c324c03e5f1ec3b4a6f3
Signed-off-by: Huaibin Yang <huaibiny@codeaurora.org>
Signed-off-by: Ingrid Gallardo <ingridg@codeaurora.org>